The Effect of Lentil-Tef Mixture on Occurrence of Adzuki Bean Beetle (Callosobruchus chinensis) and its Natural Enemy in Stored Lentil

Abstract

Abstract
Laboratory experiment was conducted to determine the effect of mixing lentil grain with
tef grain on the occurrence of Adzuki bean beetle (ABB), Callosobruchus chinensis and
its natural enemy in stored lentil. Brown-seed tef grain was mixed with lentil (cu. Derso)
grain on replacement basis at the rate of 0% (full lentil), 5%, 10%, 15%, 20%, 25%,
and 30% of the full lentil grain. The full lentil treatment was10 kg per bag
(polypropylene bags (40 cm x 70 cm)), while for the remaining treatments the required
amount of lentil grain was removed and replaced by equal amount of tef grain. Each
treatment was replicated three times and was arranged in randomized complete block
design. From each bag 25 lentil grain samples were randomly selected approximately at
monthly intervals and examined for the presence or absence of ABB eggs, ABB
emergence holes and its natural enemy emergence holes. Tef grain mixed (up to 30%)
with lentil grain had no influence on the percentage of grains with ABB eggs (%); ABB
eggs per grain; grains with emergence hole (%); ABB emergence hole per grain; and
natural enemy emergence hole per grain. Dinarmus basalis, which is a new record to
Ethiopia, and Anisopteromalus calandrae were the ectoparasitoids that attacked ABB
larvae in stored lentil. The proportion of ABB larvae parasitized by the two natural
enemies together ranged from 18% to 66%. Since ABB was able to infest, reproduce,
and complete multiple generations on lentil irrespective of the amount of tef mixed,
farmer should be informed about the ineffectiveness of the traditional method they apply
to control Adzuki bean beetle in stored lentil.